fix(shields): Add note about Cradio pin arrangement

app/boards/shields/cradio/README.md

@@ -1 +1,35 @@
+# Cradio
+
 Cradio is a firmware for a few 34 key keyboards, including Cradio, Hypergolic and Sweep.
+
+## Pin arrangement
+
+Some revisions of the aforementioned PCBs have slightly different pin arrangements compared to what's defined in [`cradio.dtsi`](./cradio.dtsi). If you need to swap a few keys for your particular PCB, you can easily reorder the `input-gpio` definition in your own keymap file (i.e. in `zmk-config/config/cradio.keymap`):
+
+```dts
+/* Adjusted Cradio pin arrangement */
+/* The position of Q and B keys have been swapped */
+&kscan0 {
+	input-gpios
+	= <&pro_micro_d  6 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_a  0 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_a  1 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_a  2 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_a  3 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_d 15 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_d 14 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_d 16 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_d 10 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_d  1 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_d  2 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_d  3 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_d  4 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_d  5 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_d  7 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_d  8 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	, <&pro_micro_d  9 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>
+	;
+};
+```
+
+This `&kscan0` block must be placed outside of any blocks surrounded by curly braces (`{...}`).